As surgical knowledge and techniques have progressed, there has been a corresponding trend toward size reduction of surgical incisions and invasive instruments, thus decreasing patient trauma and contributing to rapidity of patient recovery. This has led to the practice of laparoscopic and other surgical procedures using small medical electrodes. The incidence of AIDS and other highly dangerous or fatal communicable diseases has highlighted the importance of using either discardable components or of thoroughly sterilizing those that are used more than once.
To protect against the spread of disease, while at the same time reducing the overall cost of surgical equipment, a variety of electrosurgical techniques and implements have heretofore been proposed, illustrative of which are those described in U.S. Pat. No. 1,916,722 to Ende, issued Jul. 4, 1933; German Patent Application 2,404,764 to Weissman et al., published Sep. 19, 1974; U.S. Pat. No. 5,531,743 to Nettekoven et al, issued Jul. 2, 1996; U.S. patent application Ser. No. 08/547,571 by Nettekoven, filed Oct. 24, 1995; PCT International Application No. 82/0084, filed on Jan. 25,1982 by William S. Walker; and PCT International Application No. 91/05520 filed on Aug. 2, 1991 by Edwin Langberg. According to proposals of these patents, multi-element implements have included reusable bodies with removable and disposable tips or electrodes. The main bodies or holders may be sterilized if needed and re-used, and the tips, blades or electrodes may be discarded after a single use or sterilized and re-used.
The multi-element electrosurgical instruments found in the prior art, however, generally suffer from some significant limitations and drawbacks. For example, some of the devices found in the prior art include a relatively simple press-fit or frictional connection between a disposable tip and a reusable electrode shaft, which has several disadvantages. First, such a connection may allow the tip to become inadvertently separated from the shaft during a surgical procedure, which poses a danger to the patient and may require further and even more invasive surgical procedures to retrieve the separated tip. Another limitation is that such a connection may permit the tip to rotate relative to the shaft during use. Because many electrosurgical tips are asymmetrical, fixing the position of the tip relative to the shaft assists the physician in properly orienting the tip during a surgical procedure, thereby enabling the surgeon to more precisely position the surgical tip at the desired surgical location of the patient during a procedure. Further, many devices found in the prior art suffer from the fact that the tip is often not rigidly secured to the end of the shaft. It will be appreciated that the feel of the instrument in the hand of the surgeon is extremely important and that any play in the connection between the disposable tip and the shaft is, therefore, undesirable. Further still, many of the devices found in the prior art do not adequately insulate the connection between the shaft and the tip so as to guard against the possibility of exposing electrically conductive surfaces, which may come into contact with the patient during a procedure, provide an unintended conduction path to the patient, and result in inadvertent burns or cuts in the vicinity of the surgical site. This is of particular concern in relation to electrosurgical instruments adapted for laparoscopic procedures, where such unintended burns or cuts may occur outside of the limited field of vision afforded the surgeon by the laparoscope. Accordingly, there has continued to be a need for an improved resposable electrosurgical instrument comprising a reusable electrode shaft, a disposable tip and an improved coupling therebetween, which overcomes these limitations and disadvantages.